Peterson 1935 sage brush-covered gentle slope, mostly gravelly but with some sandy patches. July 21. Cobra, 6100 ft., Elko Co., Nevada Catch consisted of 42 Peromyscus m. sonoriensis, one Perognathus p. olivaceus, one Microdipodops megacephalus, one Neotoma lepida, one Dipodomys m. leipes and one Dipodomys o. columbianus. Pack up & leave for site 4 mi. W of Halleck on bank of arrive here about 10:30 a. m. Camp pitched, specimens which were gutted + sexed immediately before leaving were attended to. Skins prepared of all animals obtained save 39 Peromyscus m. sonoriensis which were discarded. 80 mouse traps set on sandy + gravelly slope + flat W of N Fork of Humboldt River. July 22. 4 mi. W Halleck, 5200 ft., Elko Co., Nevada Catch consisted of 3 Dipodomys m. leipes, 3 Microdipodops megacephalus and 3 Eutamias m. scrutator. Skins prepared of 3 Eutamias m. scrutator, and one Thomomys t. nevadensis caught by Dr. Hall + Mr. Richardson. Skeleton prepared of one Onychomys l. brevicaudus caught by